Converted CFX_Matrix::TransformRect() to take in consts

Currently, all three of CFX_Matrix::TransformRect() take in rect values
and modify them in place.

This CL converts them to take in constant values and return the
transformed values instead, and fixes all the call sites.

Bug=pdfium:874

Change-Id: I9c274df3b14e9d88c100ba0530068e06e8fec32b
Reviewed-on: https://pdfium-review.googlesource.com/11550
Reviewed-by: dsinclair <dsinclair@chromium.org>
Commit-Queue: Jane Liu <janeliulwq@google.com>

2 files changed, 43 insertions, 31 deletions

diff --git a/core/fxcrt/fx_coordinates.cpp b/core/fxcrt/fx_coordinates.cpp
index 26c9169fd9..b3d0432e1c 100644
--- a/core/fxcrt/fx_coordinates.cpp
+++ b/core/fxcrt/fx_coordinates.cpp
@@ -313,9 +313,7 @@ float CFX_Matrix::GetYUnit() const {
 }
 
 CFX_FloatRect CFX_Matrix::GetUnitRect() const {
-  CFX_FloatRect rect(0, 0, 1, 1);
-  TransformRect(rect);
-  return rect;
+  return TransformRect(CFX_FloatRect(0.f, 0.f, 1.f, 1.f));
 }
 
 float CFX_Matrix::TransformXDistance(float dx) const {
@@ -338,33 +336,47 @@ CFX_PointF CFX_Matrix::Transform(const CFX_PointF& point) const {
   return CFX_PointF(a * point.x + c * point.y + e,
                     b * point.x + d * point.y + f);
 }
-
-void CFX_Matrix::TransformRect(CFX_RectF& rect) const {
-  float right = rect.right(), bottom = rect.bottom();
-  TransformRect(rect.left, right, bottom, rect.top);
-  rect.width = right - rect.left;
-  rect.height = bottom - rect.top;
-}
-
-void CFX_Matrix::TransformRect(float& left,
-                               float& right,
-                               float& top,
-                               float& bottom) const {
+std::tuple<float, float, float, float> CFX_Matrix::TransformRect(
+    const float& left,
+    const float& right,
+    const float& top,
+    const float& bottom) const {
   CFX_PointF points[] = {
       {left, top}, {left, bottom}, {right, top}, {right, bottom}};
   for (int i = 0; i < 4; i++)
     points[i] = Transform(points[i]);
 
-  right = points[0].x;
-  left = points[0].x;
-  top = points[0].y;
-  bottom = points[0].y;
+  float new_right = points[0].x;
+  float new_left = points[0].x;
+  float new_top = points[0].y;
+  float new_bottom = points[0].y;
   for (int i = 1; i < 4; i++) {
-    right = std::max(right, points[i].x);
-    left = std::min(left, points[i].x);
-    top = std::max(top, points[i].y);
-    bottom = std::min(bottom, points[i].y);
+    new_right = std::max(new_right, points[i].x);
+    new_left = std::min(new_left, points[i].x);
+    new_top = std::max(new_top, points[i].y);
+    new_bottom = std::min(new_bottom, points[i].y);
   }
+  return std::make_tuple(new_left, new_right, new_top, new_bottom);
+}
+
+CFX_RectF CFX_Matrix::TransformRect(const CFX_RectF& rect) const {
+  float left;
+  float right;
+  float bottom;
+  float top;
+  std::tie(left, right, bottom, top) =
+      TransformRect(rect.left, rect.right(), rect.bottom(), rect.top);
+  return CFX_RectF(left, top, right - left, bottom - top);
+}
+
+CFX_FloatRect CFX_Matrix::TransformRect(const CFX_FloatRect& rect) const {
+  float left;
+  float right;
+  float top;
+  float bottom;
+  std::tie(left, right, top, bottom) =
+      TransformRect(rect.left, rect.right, rect.top, rect.bottom);
+  return CFX_FloatRect(left, bottom, right, top);
 }
 
 void CFX_Matrix::ConcatInternal(const CFX_Matrix& other, bool prepend) {
diff --git a/core/fxcrt/fx_coordinates.h b/core/fxcrt/fx_coordinates.h
index cc14508d70..a4074a4afa 100644
--- a/core/fxcrt/fx_coordinates.h
+++ b/core/fxcrt/fx_coordinates.h
@@ -8,6 +8,7 @@
 #define CORE_FXCRT_FX_COORDINATES_H_
 
 #include <algorithm>
+#include <tuple>
 
 #include "core/fxcrt/fx_basic.h"
 
@@ -672,14 +673,13 @@ class CFX_Matrix {
 
   CFX_PointF Transform(const CFX_PointF& point) const;
 
-  void TransformRect(CFX_RectF& rect) const;
-  void TransformRect(float& left,
-                     float& right,
-                     float& top,
-                     float& bottom) const;
-  void TransformRect(CFX_FloatRect& rect) const {
-    TransformRect(rect.left, rect.right, rect.top, rect.bottom);
-  }
+  std::tuple<float, float, float, float> TransformRect(
+      const float& left,
+      const float& right,
+      const float& top,
+      const float& bottom) const;
+  CFX_RectF TransformRect(const CFX_RectF& rect) const;
+  CFX_FloatRect TransformRect(const CFX_FloatRect& rect) const;
 
   float a;
   float b;